DuPage Airport air traffic controllers won't fly solo on the midnight shift any more, as federal authorities react to news of a sleeping on the job incident in Nevada, one of several recently.

The Federal Aviation Administration is putting additional controllers at 27 towers across the country that up until now only had one person on overnight shifts.

The action comes after a controller fell asleep Wednesday morning at the Reno-Tahoe International Airport tower as a medical flight with a sick patient was trying to land. The flight landed safely with assistance from another air-traffic facility in Northern California.

The FAA's move on Wednesday will not affect O'Hare or Midway International Airports, which have more than one person on midnight shifts. The O'Hare main tower is staffed from midnight to 6 a.m. with a supervisor and three controllers; Midway has two controllers for the same time slot.

The DuPage Airport had been staffed with one controller on midnight shifts.

"We absolutely cannot and will not tolerate sleeping on the job," FAA Administrator Randy Babbitt said, while U.S. Department of Transportation Secretary Ray LaHood said he was "outraged by these incidents."

The National Air Traffic Controllers Association said Wednesday they supported the extra manpower at towers. The union previously has called one-person shifts unsafe.

Earlier in March, union regional vice president for the Great Lakes region Bryan Zilonis said the number of hours or consecutive shifts a controller works plays a role in fatigue.

"It's a concern for us," he said.

On Monday, a controller at Boeing Field/King County International Airport in Seattle dropped off during a morning shift.

On March 23, a controller working alone at Ronald Reagan National Airport on the night shift fell asleep and could not be contacted by two incoming aircraft.